Permutation of Objects
The number of ways n distinct objects can be ordered is n.
Example:
Number of ways 6 people can from a queue is 6.
Number of ways 5 different cars can be parked in 5 parking spaces is 5.
Remember:
This does not apply if there are identical objects or ordering does not matter.
Permutation with Selection
The number of ways n objects drawn from a collection of m distinct objects can be ordered is m!/(m-n).
Example:
Number of ways a queue of length 3 can be formed from a group of 5 people is 5!/(5-3)!=5!/2!=5*4*3=60.
Number of possible top ten list for 150 movies is 150!/(150-10).
Remember:
This does not apply if there are identical objects or ordering does not matter.
